1. Field of the Invention
The present invention relates to a washing and disinfecting method and apparatus for artificial dialyzer used for patients suffering from renal disease.
2. Related Background Art
Artificial dialysis is to artificially purify the blood, which is guided out of a patient suffering from renal disease, by means of an artificial dialyzer. For example, an apparatus is arranged to introduce a solution A of a raw solution for dialysis composed mainly of a potassium chloride solution, a sodium chloride solution, or the like, a solution B of a sodium bicarbonate solution, and a clean water (a water let to pass through a reverse osmotic membrane to remove various germs, which is hereinafter sometimes referred to as "RO water") thereinto, as shown in FIG. 3. Then, the solution A, solution B, and clean water are mixed at the ratio of 1:2:32, thereby preparing a dialyzing fluid. After a concentration of the dialyzing fluid is checked, it is once stored in a reservoir. After the concentration of the dialyzing fluid is again checked, it is fed to each console, with which a patient is subjected to dialysis treatment. Each console uses the dialyzing fluid to continuously dialyze the blood of patient while continuously washing the reverse osmotic membrane (located outside the drawing).
In FIG. 3, reference numeral 100 designates an inlet for clean water (RO water), 101 an inlet for solution A, 102 an inlet for solution B, 103 a measuring cup for solution A, 104 a measuring cup for solution B, 105 a mixing tank, 106 a reservoir, 107, 108 concentration meters, 109-112 float switches mounted to associated cups or tanks, 113, 114, 115, and 130 electromagnetic valves, 116-118 motor-operated valves, 119-123 pumps, and 124, 125 manual valves.
Further, reference numeral 126 designates a pressure gauge, and 127 a thermometer. The dialyzer is composed of separate parts, i.e. a central part for controlling mixing of the dialyzing fluid and feeding thereof, and a console box part, which is connected to the central part through pipe lines, for receiving supply of the dialyzing fluid from the central part and effecting dialysis of the patient's blood through the osmotic membrane.
The artificial dialyzer as described above is used to perform hemodialysis usually at frequency of once a week to once every few weeks in accordance with the stage of disease of patient. Further, since the artificial dialyzer requires a high-level control, it is a present status that a plurality of patients use a single dialyzing apparatus by turns. Namely, the patients suffering from renal disease individually go to the facilities named as a dialysis center equipped with a plurality of artificial dialyzers, and some patients use one artificial dialyzer by turns for prescribed hemodialysis.
Accordingly, sufficient attention must be paid to infection to various infectious diseases through the apparatus for artificial dialysis. Heretofore, immediately after completion of the dialyzing operation, the dialyzing fluid is drained and post-washing is conducted with the clean water. After the clean water is drained, a disinfecting operation is conducted with a disinfectant, thereby preparing for a next dialyzing operation. Then, before conducting the next dialyzing operation, further pre-washing is conducted in order to prevent infection from occurring through the apparatus for dialysis. Thus, the dialyzer is kept as carefully washed and disinfected.
Namely, as shown in FIG. 4, the conventional washing and disinfecting operation for dialyzer is conducted as follows. The clean water inlet (RO water inlet) 100, a boiling water inlet 22, the sodium bicarbonate solution inlet 102, a disinfectant inlet 21, and the raw solution inlet 101 are preliminarily connected to the apparatus. The dialyzing fluid stored in the mixing tank 105 and the reservoir 106 is drained by sequence control in a predetermined period. Then, hot water or boiling water is input into the apparatus and kept for a few or ten minutes, and the input hot water or boiling water is drained. After the washing operation, a disinfectant comprised of a sodium hypochlorite solution (0.01-0.02%) is introduced and retained as it is until the next dialysis, thereby effecting wash and disinfection of the dialyzer comprised of the tanks, pipe lines, valves, etc.
Then, before the next dialysis operation, the disinfectant retained is drained, and thereafter the apparatus is filled with boiling water or hot water having passed through a reverse osmotic membrane for a few or ten minutes. Further, the clean water is introduced for a few or ten minutes to wash the apparatus, and then the dialyzing operation is conducted. Thus, every effort is made to prevent infection from occurring.
Furthermore, an acetic acid solution (0.1%) is poured into the apparatus once or twice a week to remove calcium, etc. adhering to the pipe lines, etc. In addition, a formalin solution is poured into the apparatus about once a month to perfect the disinfection.
FIG. 4 shows the flow of the medical fluid for washing and disinfecting the pipe line system including the mixing tank 105 and reservoir 106 when the disinfectant is injected and circulated. The clean water (RO water) and disinfectant each flow in the predetermined order at a predetermined interval through the tanks, the hemodialyzer portions having the osmotic membranes, and the pipe lines, thereby washing and disinfecting the tanks, the pipe lines, and the dialyzing portions of the osmotic membranes.
Further, FIG. 5 is a schematic and perspective view to show the central part of the artificial dialyzer as described above. The same numbers in FIG. 5 as those in FIG. 3 and FIG. 4 denote the same portions as in FIG. 3 and FIG. 4. The apparatus of FIG. 5 is provided with the pipe lines, pumps, and valves for injecting, circulating, and retaining the washing solutions (the disinfectant, etc.) for washing and disinfecting the artificial dialyzer, similar to those shown in FIG. 4, in addition to the fundamental structure as shown in FIG. 3.
However, bacteria, fungi, viruses, etc. in the dialyzer were not able to be eliminated completely therefrom even by a long-term washing and disinfecting operation for one to three hours using the disinfectants mainly of the sodium hypochlorite solution and the acetic acid solution before and after dialysis, thus failing to perfectly suppress occurrence of infectious disease. Particularly, there were the following problems. A nutrition source, such as calcium, protein, etc. contained in a fine amount in the dialyzing fluid, the water, the blood, etc., adhered to the inside of the pipe lines, etc., and new various germs, etc. propagated there. There remained the toxins (enzymes) produced by the various germs, and dead bodies of bacteria per se (endotoxins) inside the pipe lines, and they were brought into the patient's body with return of the blood, which could cause the patient to have cryptogenic fervescence.
Further, the wash and disinfection with sodium hypochlorite, etc. had such a problem that adverse effects of the residual components on the human bodies and on the other environments would result after use for a long period. Furthermore, since sodium hypochlorite is alkaline, the disinfecting effect is low. Therefore, unless it were used in a concentration of about 1000 ppm, the disinfecting effect thereof would be weak. On the other hand, if it were used in such a high concentration, chlorine would remain 500 ppm or so in waste water. Therefore, the residual chlorine in the high concentration would cause serious environmental pollution. Accordingly, in order to prevent the environmental pollution, the facilities with the dialyzer need a waste water treatment for decreasing the residual chlorine of the high concentration, which forces enormous expense.